Canadian Forest Service Publications

Aerial spray trials with nuclear polyhedrosis virus and Bacillus thuringiensis on gypsy moth (Lepidoptera: Lymantriidae) in 1994. II. Impact one year after application. 1996. Cunningham, J.C.; Brown, K.W.; Scarr, T.A.; Fleming, R.A.; Burns, T. Proceedings of the Entomological Society of Ontario 127: 37-43.

Year: 1996

Issued by: Great Lakes Forestry Centre

Catalog ID: 20963

Language: English

Availability: PDF (request by e-mail)

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Aerial spray trials were conducted in Pinery Provincial Park in 1994 using Disparvirus (nuclear polyhedrosis virus (NPV)) and Foray 48B (Bacillus thuringiensis subsp. kurstaki) to control gypsy moth, Lymantria dispar (L.). The virus was formulated in Novo Nordisk Carrier 244. Dosage was a double application of 5 x 1011 polyhedral inclusion bodies (PIB)/ha (total 1012 PIB/ha) and two application volumes were tested, 5.0 L/ha and 2.5 L/ha. Foray was applied as a single application of 50 billion international units (BIU) in 4.0 L/ha. Treatments were replicated on five 10 ha plots and a further five 10 ha plots were used as untreated check plots. Reduction in egg-mass numbers, foliage protection, and pupal counts were significantly lower in all treatments than in the untreated check plots. The same plots were sampled in 1995 to determine the impact of the treatments one year after application. Samples of larvae collected weekly were diagnosed microscopically. Over the 7-week sampling period, 20.4 % (n=1,251) were positive for NPV in plots treated with Disparvirus at 5.0 L/ha, 14.6 % (n=1,529) in plots treated with Disparvirus at 2.5 L/ha, 8.0 % (n=818) in plots treated with Foray 48B and 9.2 % (n=1,577) in untreated check plots. Defoliation was negligible (< 7 %0) in all treated and check plots. The mean pupal counts in burlap traps were slightly higher in the treated plots than in 1994, but fall egg-mass counts were very low in all treated and check plots, the highest being 415 egg-masses per ha in one of the untreated check plots. The gypsy moth population collapsed in Pinery Provincial Park in 1995; NPV found in all plots was obviously a contributing factor.